Originally Posted by
Turnin_Wrenches
There is nothing inherently fatiguing about Z3. Large doses of anything without sufficient recovery will increase fatigue and hinder training.
I agree, but it’s relatively easy to rack up large amounts of TSS in Z3 if your volume is high. If your volume is relatively low then It doesn’t really matter. I note that pros do most of their volume in Z2 to manage their overall TSS and stay fresh for the higher intensity efforts. If they did all that volume in Z3 they would be overtraining.
To me Z2 and Z3 are much the same thing, but Z3 accumulates more TSS for the same volume. I find efforts at FTP or above feel very different.